Adsorption of the Herbicides Diuron, Terbacil, and Simazine to Blueberry Mulches

Abstract

<jats:p>Samples of soil, mulch, and the soil/mulch interface zone were collected from commercial highbush blueberry <jats:italic>(Vaccinium corymbosum</jats:italic> L.) fields typical in their use of mulch under Arkansas conditions. Mulches included 1-year-old hardwood sawdust, 5-year-old hardwood sawdust, and 1-year-old pine needle mulch. Herbicide adsorption (Kd values) of the samples was determined for diuron, terbacil, and simazine. The soils, mulches, and interfaces adsorbed nearly 10 times as much diuron and more than twice as much simazine as terbacil. Adsorption of the herbicides was three to five times greater to the mulches than to the soils. Adsorption was significantly correlated with the organic matter content of the mulch. Adsorption was not related to herbicide solubility. Although no statistical differences were found among the three mulch materials, adsorption coefficients (Kd values) were numerically lower for each chemical on the 5-year-old hardwood mulch than on the 1-year-old hardwood or pine mulch. Chemical names used: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron); 3- <jats:italic>tert</jats:italic> -butyl-5-chloro-6-methyluracil (terbacil); 2-chloro-4,6-bis(ethylamine)- <jats:italic>s</jats:italic> -triazine (simazine).</jats:p>

Weed Control by Spring Cover Crops and Imazethapyr in No-till Southern Pea (Vigna unguiculata)

“…This may be because the large amount of sorghumsudangrass biomass, which was twice that of Italian ryegrass and oat (Table 1), interfered with herbicide distribution. Herbicide was possibly bound in the residue (8). Except for Palmer amaranth, weed control by the half rate of imazethapyr averaged across cover crops was the same as the full rate and was consistent in 1992 and 1993 (Table 5).…”

Short-term Preemergence Herbicide Adsorption by Mulch Materials and Impacts on Weed Control

“…Herbicides generally tend to adsorb more tightly to mulch materials or soils with higher organic matter with up to five times greater adsorption being reported in mulches compared with field soils in some studies (Hodges and Talbert, 1990). Most previous research on herbicide movement or adsorption by mulch has been conducted in agronomic crops with lower levels of plant residue and with herbicides with higher solubility and K oc than were evaluated in this experiment.…”

“…Although adsorption absorption to mulch is a rapid process, desorption is typically a slow process occurring over weeks or months depending on mulch degradation, herbicide half-life and adsorption coefficients, and environmental factors, including rainfall and irrigation (Aslam et al, 2013;Hodges and Talbert, 1990;Huang et al, 2006;Selim and Zhu, 2005). As most herbicide labels indicate that 0.25 to 0.5 inch of irrigation is needed to water in herbicides following application, it is possible additional irrigation will be needed with some preemergence herbicides applied to mulched nursery containers or landscape beds.…”